Hugo Speer (Bleak House, The Full Monty) joins as Susan Penwarden's (McCutcheon) husband, Mark, who will stop at nothing to run his wife's ex-lover Daniel Marrack (Donovan) out of fictional Cornish coastal town, Polnarren.
Meanwhile, former Coronation Street veteran Johnny Briggs is to play long-term resident Fin Morgan.
Polnarren will also house a variety of familiar faces from the worlds of film and television, including Ed Speelers (Eragon), Marcus Patric (Hollyoaks), Laura Greenwood (Prime Suspect 7), Christian Cooke (Where The Heart Is), Jonathan Readwin (Robin Hood), Naomi Ryan (Dream Team), Chandeep Uppal (Anita And Me) and newcomer Hannah Lederer Alton.
Moving Wallpaper star Ben Miller will be joined by Raquel Cassidy (Party Animals, Lead Balloon), James Lance (Teachers, Sensitive Skin), Sarah Hadland (Saxondale, Peep Show), Elizabeth Berrington (The Office), Lucy Liemann (The IT Crowd), Dave Lamb (The Smoking Room) and Sinead Keenan (Trouble With Sex).
Susie Amy (Footballers' Wives, Hotel Babylon) will also appear in both series.
Echo Beach and Moving Wallpaper began filming last week and are due to air in back-to-back – Moving Wallpaper being a fictional behind-the-scenes comedic look at the filming of Echo Beach.
Click here to read more about the shows.